The subject of the present invention is an ice nucleating agent and a process for preparing such an agent.
It is known that a product can be frozen in the presence of an ice nucleating agent, at a temperature greater than that where this product would have frozen spontaneously. Indeed, ice nucleating agents promote formation of ice crystals at a temperature greater than that where these crystals would have formed without the presence of nucleating agents. Thus, such agents are up until now used in processes for freezing products, especially food products, in order to reduce the quantity of energy necessary for the freezing of these products European Patent Application Publication No. 0 424 771 A1.
It is also known that ice nucleating agents can increase the size of ice crystals during the freezing of some products (Ryder, J. M. 1987, Thesis, p155, Rhode Island University). Indeed, the ice crystals present in a product frozen with an ice nucleating agent are larger than those present in the same product frozen without such an agent. These large ice crystals leave, moreover, an imprint in the European Patent Application Publication No. 0 424 771 A1 frozen products by modifying their texture. Furthermore, this modification can be stablilized by freeze-drying followed by heating of the frozen product. Thus, ice nucleating agents are up until now used for freezing products, especially food products, in order to give an advantageous texture to the final product (Agric. Biol. Chem., 50 (1), 169-175, 1986).
Most biological nucleating agents have been found in microorganisms or insects. However, it could be very useful to isolate an ice nucleating agent from plants, especially from edible plants, for their use for the freezing, texturing or cryoconcentration of products, such as food products for example.
The aim of the present invention is to respond to this need.